To the Editor The Colloids vs Crystalloids for the Resuscitation of the Critically Ill (CRISTAL) trial1 found no difference in 28-day mortality but improved 90-day mortality in patients in the intensive care unit (ICU) with hypovolemic shock resuscitated using colloids (mainly hydroxyethyl starch solutions) vs crystalloids (mainly isotonic saline). The CRISTAL trial was unblinded and allocation of patients occurred by envelope randomization using fixed block size, which may not have ensured allocation concealment.